It has been recognized that drinking cups and other nestable containers with superior properties, especially for the retention of hot beverages, such as coffee, can be formed from expanded thermoplastic materials, the most popular of which has proven to be expanded polystyrene. Several different types of containers and methods for producing them have been proposed, and some have been successful in the marketplace.
Several design criteria which have been sought to be achieved are the elimination of postprinting of containers after they have been fabricated, the production of containers with different sidewall configurations (and different capacities) including convex and concave surfaces with minimum set up expense, and the elimination of waste materials during the production of containers.
Commonly assigned copending Amberg et al., U.S. Pat. application, Ser. No. 354,305, filed Apr. 25, 1973 now abandoned, a continuation-in-part application of application, Ser. No. 211,259 now U.S. Pat. No. 3,854,583, discloses a method and apparatus for forming a two-piece nestable cup. While the method and apparatus of this mentioned invention functions well to produce nestable cups, the need remains for a simplified and less costly method and apparatus.
Commonly assigned Amberg et al., U.S. Pat. application Ser. No. 418,562, filed concurrently herewith now U.S. Pat. No. 3,969,173 discloses a related method and apparatus for fabricating two-piece thermoplastic cups. This application discloses an advanced method and apparatus over the last mentioned Amberg et al. application which has improved upon the method of handling the web stocks which form the sidewall and bottom closure discs.